Feed device for travelling grates



March 6 HANS-WERNER ZIEGLER ETAL 3,307,679

FEED DEVICE FOR TRAVELLING GRATES Filed June 25, 1965 3 Sheets-Sheet 1JH L March 7, 1967 HANS-WERNER ZIEGLER ETAL FEED DEVICE FOR TRAVELLINGGRATES Filed June 25, 1965 3 Sheets-Sheet 2 March 1967 HANS-WERNERZIEGLYER ETAL 3,307,679

FEED DEVICE FOR TRAVELLING GRATES I Filed June 25, 1965 5 Sheets-Sheet 5United States Patent 3,307,679 FEED DEVICE FOR TRAVELLING GRATESHans-Werner Ziegler, Knapsack, near Cologne, Leo Berg,

This invention relates to a feed device for travelling grates, sinterbelts and the like which enables the height of a bed of material fedthereto to be adjusted. More particularly the invention concerns suchfeed devices of the type comprising a feeder belt adapted to be drivenat a substantially uniform speed and to be oscillated from side to sideat a variable angular velocity to vary the height of the bed of materialdesired to be placed on the rate.

g A bed of material conveyed on a travelling grate, sinter belt and thelike has a tendency to slip sideways with the result that the bed slopeslaterally, the degree of lateral sloping depending on the bed height ofthe material.

Heating or other treating gases supplied to the bed of material tendpredominantly to flow through the lateral portions of the bed ofmaterial. This results not only in heavy thermal stress to the lateralportions of the travel ling grate but also in incomplete treatment e.g.heating or calcination of the material at the centre of the bed.

This occurrence can be suppressed by modifying the profile of the bed ofmaterial, i.e. by increasing the height of the bed near the sideportions of the travelling grate.

A pro-selected profile for the bed of material can be obtained by meansof a scraper plate provided with appropriately shaped cutouts. However,using such a scraper plate necessitates initially supplying morematerial to the side portions than to the centre portion of a grate, andthe material must be able to withstand to some extent pressure applied.thereto. Materials of low pressure resistance, e.g. briquetted materialsand uncalcined granular particles, become smashed under the action ofthe scraper or .are at least subject to deformation or degradation. Itis therefore expedient to feed the material so as to form a bedapproximating to the profile desired to be obtained. The action of thescraper plate, which may be designed, for example, as a deflector orratchet, should be limited to successive minor levelling of the bed ofmaterial, especially in the centre portion thereof. An example of such ascraper is shown in FIGURE 2 of British Patent No. 913,796.

Feed devices are known which employ a periodically oscillating anduniformly charged conveyor belt to permit of substantially evendistribution of material on a sinter belt. However, as the angularvelocity of the oscillatory motion of the conveyor belt has been unequaldue to crank drives being usually employed, and due to the direction ofmotion being reversed at the two dead points, it has been necessary touse special means for varying the periodic oscillatory motion to achievethe desired distribution of material across the whole width of thetravelling grate. To this end, it has been proposed to use a variablegear unit provided with elliptical gear wheels or a driving rod designedto automatically change its length during operation. As described inBritish Patent No. 885,633, a variable gear unit permitting the reducinggear ratio to be periodically varied is interposed between a drive motorrunning uniformly in one direction and an associated crank shaft.

The present invention now provides a feed device for travelling gratesand the like which enables a bed of material placed thereon to beadjusted in height, comprising a periodically reciprocating, uniformlycharged conveyor feed belt which is (a) designed so as to feed materialacross the whole width of the travelling grate, (b) arranged to bepivotable around a vertical pivot pin ad.- jacen-t its charge end, and(c) provided with rollers running on an arcuate rail which providessupport for the conveyor feed belt near its discharge end, means beingprovided which permits the angular velocity of the periodic oscillatorymotion of the conveyor feed belt to be varied.

The present invention provides more especially a conveyor feed belthaving operatively coupled thereto, towards its discharge end, the twoends of a cable or the like which is caused by reversible drive meansalternately to change its direction of motion so as to oscillate theconveyor feed belt. Electric limit switches, arranged at predeterminedpositions, and actuated'by the impact of the conveyor feed belt uponcontact of the conveyor therewith, limit the oscillatory motion. Thelimit switches are connected to time relays so as to enable the dwellingtime of the conveyor belt at the extreme of its travel to be varied.

The reversible drive means comprises an electric drive motor adapted torun .at a substantially uniform speed in one direction, and a reversinggear unit electromagnetically coupled thereto.

A feed device in accordance with the present invention is showndiagrammatically in the accompanying drawings, wherein:

FIGURE 1 is a cross-sectional view of a travelling grate charged with auniformly high bed of material;

FIGURE 2 is a cross-sectional view of a travelling grate indicating themanner in which a bed of material thereon tends to slip sideways;

FIGURE 3 is .a cross-sectional view of a travelling grate with a bed ofmaterial increased in height near the lateral portions of the grate;

FIGURE 4 is a side elevational view of the feed device;

FIGURE 5 is a plan view of the feed device; and FIGURE 6 is a rear viewof the feed device seen in the direction of motion of the conveyor feedbelt and travelling grate.

Referring to the drawings an endless belt conveyor 2 is arranged to beoscillated between positions indicated at a and 0: in a pivot bearing 3about a vertical axis. The conveyor is also arranged to be variablyinclined with respect to the horizontal, by pivoting about a horizontalpivot axis 4, to vary the height of the discharge end of the conveyorbelt above a travelling grate 1. The degree of adjustment provided isindicated at Ah in FIG- URE 4. The conveyor 2 is secured towards itsdischarge end in a slot 19 in a frame 5 so as to enable the conveyortobe set at a selected angle of inclination with respect to thehorizontal. This angle of inclination is adjusted whenever it is desiredto vary the height of material 20 placed on the travelling grate 1. InFIGURE 4, for example, the conveyor 2 when in the position indicated bythe solid line results in a bed of .a height H being provided on thegrate 1, and when in the position indicated by the dotted line resultsin a bed of a height H being provided.

The frame 5 has a pair of rollers 6 mounted in tandem arrangementthereon to run on arcuate rail 7 which lies on a circle whose centre isthe vertical axis of the pivot bearing 3.

The rail 7 is secured by means of one or more hangers 8 to a stationaryconstructional element 9.

The conveyor 2 is oscillated or swung from side to side about thebearing 3 by means of a cable 15 guided by cable rollers 14, the twoends of the cable being secured by means of damping springs 16 to an arm13 of the frame 5. An electric motor 17, which in use is run at asubstantially uniform speed, in one direction, and iselectromagnetically coupled to a reversing gear uni-t 18, drives thecable 15 causing it to perform a periodically reciprocating motioncarrying the conveyor 2 with it.

The rail 7 has limit switches 10 associated with it, the switches beingelectrically connected to time relays. (Not shown.) The switches 10 aredisposed at preselected points of reversal for the oscillatory motion,and are arranged to be operated when contacted. by the conveyor. When alimit switch is operated, the electromagnetic coupling for one directionof motionformerly in engaged positin-is switched off, and theoscillatory motion interrupted. At the same time, its associated timerelay is actuated, which, after a pre-selected period, actuates theelectromagnetic coupling for the reverse direction of motion. Thisoperation is continuously repeated.

Any breakdown is controlled by special overrunning switches 11 arrangedafter the limit switches in the direction of the oscillatory motion. Onbeing contacted by the conveyor 2, they switch off the drive motor 17and simultaneously operate an alarm. The rail 7 also has mechanicalstops12 still further to improve the safety of operation.

The feed device of the present invention enables material uniformly fedby the conveyor feed belt, for example, crude phosphate shapes preparedon a granulating plate, to be distributed across the travelling grate 1in such a manner that the bed of material formed thereon, is higheradjacent the points of reversal of the oscillatory motion of theconveyor than elsewhere. These points are of course determined by thepositions of the limit switches ltl, and the time during which theconveyor is allowed to dwell at those points and thus the amount ofmaterial supplied to the adjacent regions of the grate, is determined bythe setting of the time relays.

The dwelling time can be varied within wide limits. More especially, itmay vary between 3 and 10 seconds as e.g. in a plant operated byapplicants. In this plant, it has proved expedient to use mercuryswitches as the limit switches because their susceptibility todisturbances and dust is limited.

The number of limit switches associated with the rail 7, is not limitedto two, and more limit switches with time relays can be provided ifdesired which then permits a bed of material of any required profile tobe obtained,

We claim:

1. A feeding device for a travelling grate which enables the profile ofa bed of material supplied upon said grate to be controlled, saidfeeding device comprising a conveyor, said conveyor being mounted. upona pivot having a vertical axis disposed adjacent the charging end ofsaid conveyor, the discharge end of said conveyor being oscillatableabove said travelling grate, limit means cooperating with said conveyorfor adjusting the oscillation of said discharge end of said conveyoracross the entire width of said travelling grate, an arcuate guide raildisposed adjacent the discharge end of said conveyor, bracket meansconnected to support said conveyor, said bracket means including rollermeans engaging said arcuate guide rail for carrying said discharge endof said conveyor in an arcuate path, drive means attached to saiddischarge end of said conveyor for oscillating it back and forth uponsaid arcuate guide rail, said drive means includes a motor, motiontransmitting means connecting said motor to said discharge end of saidconveyor, said limit means including limit switches being connected tosaid motion transmitting means, and time delay relays being connected tosaid limit switches to permit the dwelling time of the discharge end ofsaid conveyor .at its extremes of travel to be adjusted whereby theprofile of said bed of material at said sides is adjusted relative tosaid profile at said center of said travelling grate.

2. A feeding device as set forth in claim 1 wherein said motor is auniformly and unidirectionally running motor, said motion transmittingmeans is reversible and comprises a pulley and cable linkage from saiddrive motor to said discharge end of said conveyor means.

3. A feeding device as set forth in claim 2 wherein said pulley andcable linkage is connected to said bracket means.

4. A feeding device as set forth in claim 3 wherein said limit switchesare disposed in the path of movement of said roller means.

5. A device as claimed in claim 1, wherein the reversible drive motorcomprises an electric drive motor adapted to run in one direction at asubstantially uniform speed and a reversing gear unitel-ectromagnetically coupled thereto.

References Cited by the Examiner UNITED STATES PATENTS 1,038,588 9/1912Iverson 198-125 X EVON C. BLUNK, Primary Examiner.

EDWARD A. SROKA, Assistant Examiner.

1. A FEEDING DEVICE FOR A TRAVELLING GRATE WHICH ENABLES THE PROFILE OF A BED OF MATERIAL SUPPLIED UPON SAID GRATE TO BE CONTROLLED, SAID FEEDING DEVICE COMPRISING A CONVEYOR, SAID CONVEYOR BEING MOUNTED UPON A PIVOT HAVING A VERTICAL AXIS DISPOSED ADJACENT THE CHARGING END OF SAID CONVEYOR, THE DISCHARGE END OF SAID CONVEYOR BEING OSCILLATABLE ABOVE SAID TRAVELLING GRATE, LIMIT MEANS COOPERATING WITH SAID CONVEYOR FOR ADJUSTING THE OSCILLATION OF SAID DISCHARGE END OF SAID CONVEYOR ACROSS THE ENTIRE WIDTH OF SAID TRAVELLING GRATE, AN ARCUATE GUIDE RAIL DISPOSED ADJACENT THE DISCHARGE END OF SAID CONVEYOR, BRACKET MEANS CONNECTED TO SUPPORT SAID CONVEYOR, SAID BRACKET MEANS INCLUDING ROLLER MEANS ENGAGING SAID ARCUATE GUIDE RAIL FOR CARRYING SAID DISCHARGE END OF SAID CONVEYOR IN AN ARCUATE PATH, DRIVE MEANS ATTACHED TO SAID DISCHARGE END OF SAID CONVEYOR FOR OSCILLATING IT BACK AND FORTH UPON SAID ARCUATE GUIDE RAIL, SAID DRIVE MEANS INCLUDES A MOTOR, MOTION TRANSMITTING MEANS CONNECTING SAID MOTOR TO SAID DISCHARGE END OF SAID CONVEYOR, SAID LIMIT MEANS INCLUDING LIMIT SWITCHES BEING CONNECTED TO SAID MOTION TRANSMITTING MEANS, AND TIME DELAY RELAYS BEING CONNECTED TO SAID LIMIT SWITCHES TO PERMIT THE DWELLING TIME OF THE DISCHARGE END OF SAID CONVEYOR AT ITS EXTREMES OF TRAVEL TO BE ADJUSTED WHEREBY THE PROFILE OF SAID BED OF MATERIAL AT SAID SIDES IS ADJUSTED RELATIVE TO SAID PROFILE AT SAID CENTER OF SAID TRAVELLING GRATE. 